共查询到19条相似文献,搜索用时 62 毫秒
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巯基乙酸异辛酯是一种广泛应用于精细化工、树脂和塑料制造的中间体,尤其在聚氯乙烯无毒制品中有着重要用途[1],其合成方法的改进也成为研究的主要课题之一。巯基乙酸异辛酯的合成通常采用硫酸催化法[2],由于浓硫酸污染环境、腐蚀设备,特别是近年来环保法规对环境和安全性不断提高的要求,用固体酸(分子筛、离子交换树脂、固体超强酸)等取代H2SO4、HF、A lC l3等强腐蚀性酸作为催化剂的催化工艺获得明显进展[3],但这些催化剂也有自身的缺点[4]。室温离子液体是近年来受到极大关注的一类新材料,它为人们探索环境友好的催化体系和溶剂提供了… 相似文献
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本文以2-甲基咪唑、溴乙烷、L-谷氨酸为原料合成新型的咪唑谷氨酸盐离子液体,并对其进行红外光谱、核磁共振、质谱表征,同时将其代替浓H2SO4用于催化乙酸酐和水杨酸的乙酰化反应。探究了离子液体的用量、反应温度、反应时间对阿司匹林合成的影响和该氨基酸离子液体的重复使用性能。结果表明:该离子液体对于合成阿司匹林具有良好的催化效果,在水杨酸为2.76g;乙酸酐为4.083g;氨基酸离子液体用量为3滴、反应温度70℃、反应时间30min的条件下,阿司匹林的产率可达78.2%。 相似文献
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用Bronsted酸性离子液体[Hmim]BF4、[bmim]HSO4和[bmim]H2PO4代替浓H2SO4为催化剂催化乙酸酐对水杨酸的乙酰化,合成阿司匹林.考察了反应温度、反应时间、催化剂用量、酐/醇摩尔比对水杨酸酰化反应产率的影响和离子液体的重复使用性能.选择了最佳反应条件,以[bmim]H2PO4作为催化剂,催化剂用量为0.28
g(1.18×10-3mol),水杨酸2.762 g(0.02 mol),乙酸酐4.083 g(0.04 mol),n(酐)n(醇)=21,反应时间30
min,反应温度70℃,产率最高达63.43%,并且[bmim]H2PO4溶于水后通过过滤和旋蒸脱水,重复使用3次,产率无明显变化. 相似文献
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对价格昂贵的手性催化剂进行回收和重复利用是目前不对称催化领域面临的难题之一,受到学术界和工业界的共同关注。化学家们已经尝试了许多方法,其中使用离子液体来替代常规有机溶剂使催化剂得到分离和重新使用已经引起他们极大的兴趣。本文综述了近年来在离子液体中进行不对称催化反应的研究进展,对离子液体中过渡金属和有机小分子催化的各种反应进行重点介绍,强调了离子液体不但在催化剂回收方面有独特优势,而且在许多反应中能够提高催化效率。 相似文献
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Silica-gel-confined ionic liquids: a new attempt for the development of supported nanoliquid catalysis 总被引:8,自引:0,他引:8
A new concept of designing and synthesizing highly dispersed ionic-liquid catalysts was developed through physical confinement or encapsulation of ionic liquids (with or without metal complex) in a silica-gel matrix through a sol-gel process. We studied ionic liquids such as EMImBF4, BuMImBF4, DMImBF4, CMImBF4, BuMImPF6, either with or without [Pd(PPh3)2Cl2] and [Rh(PPh3)3Cl], in a silica-gel matrix (E = ethyl, Bu = butyl M = methyl, D = decyl, C = cetyl and Im = imidazolium). The contents of ionic liquids and loadings of Pd or Rh were 8-53 wt % and 0.1 approximately 0.15 wt %, respectively. Analyses of FT-Raman spectra showed that abnormal Raman spectra of the confined ionic liquids were observed in comparison with the bulk and pure ionic liquids. EMImBF4 and BuMImBF4 ionic liquids could be completely washed out from the silica-gel matrix under vigorous reflux conditions, but ionic liquids with larger molecular size, for example, DMImBF4 or CMImBF4, could be confined into the silica-gel nanopores relatively firmly. These results suggested that the ionic liquids were physically confined or encapsulated into the silica gel. The N2 adsorption measurements indicated that the silica-gel skeleton was mesoporous with 50-110 A pore size after the BuMImBF4 ionic liquid was removed completely. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis showed that the silica-gel matrix was amorphous and non-uniformly mesoporous. Carbonylation of aniline and nitrobenzene for synthesis of diphenyl urea, carbonylation of aniline for synthesis of carbamates, and oxime transformation between cyclohexanone oxime and acetone were used as test reactions for these catalysts. Catalytic activities were remarkably enhanced with much lower amounts of ionic liquids needed with respect to bulk ionic-liquid catalysts or silica-supported ionic-liquid catalysts prepared with simple impregnation, in which the ionic liquid may be deposited as a thin layer on the support. Such unusual enhancement in catalytic activities may be attributed to the formation of nanoscale and high-concentration ionic liquids due to the confinement of the ionic liquid in silica gel; this results in unusual changes in the symmetry and coordination geometry of the ionic liquids. 相似文献
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Applications of functionalized ionic liquids 总被引:2,自引:0,他引:2
LI Xuehui ZHAO Dongbin FEI Zhaofu & WANG Lefu . Department of Chemical Engineering Guangdong Provincial Laboratory of Green Chemical Technology South China Uni-versity of Technology Guangzhou China . Swiss Federal Institute of Technology Lausanne EPFL CH- Lausanne Switzerland . PKU Green Chemistry Center Beijing National Laboratory for Molecular Sciences College of Chemistry Molecular Engineering Peking University Beijing China 《中国科学B辑(英文版)》2006,49(5):385-401
Recent developments of the synthesis and applications of functionalized ionic liquids (including dual-functionalized ionic liquids) have been highlighted in this review. Ionic liquids are at-tracting attention as alternative solvents in green chemistry, but as more functionalized ILs are pre-pared, a greater number of applications in increasingly diverse fields are found. 相似文献
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探讨了微波辐射下四种咪唑类离子液体催化不同取代基芳香醛的安息香缩合反应,并对反应条件进行了优化。结果表明,[Bmim]Im是合成目标产物的良好催化剂,在微波辐射时间5min、反应温度55℃、催化剂用量x([Bmim]Im)=1%、溶剂THF15m L、芳香醛用量5mmol、50%氢氧化钠水溶液0.5m L时,最高产率可达到81%。该方法耗时短、环境友好。在考查的底物中,除高位阻和具有较强p-π共轭效应的2-氯苯甲醛和4-甲氧基苯甲醛没有检测到产物外,其他不同取代芳香醛均得到了相应产物。反应后离子液体可以回收循环使用至少4次。 相似文献
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Synthesis of traditional and ionic polymethacrylates by anion catalyzed group transfer polymerization 下载免费PDF全文
Veronika Strehmel Volker Senkowski 《Journal of polymer science. Part A, Polymer chemistry》2015,53(24):2849-2859
The hydrophobic ionic liquid 1‐butyl‐1‐methylpyrrolidinium bis(trifluoromethylsulfonyl)imide was successfully used as solvent in group transfer polymerization of traditional methacrylates (methyl methacrylate, n‐butyl methacrylate, and benzyl methacrylate) and of ionic liquid methacrylates (ILMAs). This demonstrates that this ionic liquid makes reaction conditions, which do not require the use of ultra‐dried solvents. The ILMAs were N‐[2‐(methacryloyloxy)ethyl]‐N,N‐dimethyl‐N‐alkylammonium bis(trifluoromethylsulfonyl)imides bearing methyl, ethyl, propyl, butyl, or hexyl substituents. Increasing size of the alkyl substituent at the cation results in decreasing glass transition temperature in case of both ionic liquid methacrylates and polymers derived of them. Furthermore, the glass transition temperature is significantly higher for these polymers compared with the ionic liquid methacrylates, and the effect of glass transition temperature reduction with increasing size of the alkyl substituent is stronger for the polymers. A mechanism was proposed explaining the catalytic function of the ionic liquid used as solvent for polymerization. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2849–2859 相似文献
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The iron containing ionic liquid 1-butyl-3-methylimidazolium tetrachloroferrate ([C4mim]Cl/FeCl3; = 0.5) proved to be an efficient catalyst for the solvent-free metal catalyzed Michael addition of β-keto esters and enones. Due to the ionic structure of the catalyst, a significant acceleration of the reaction rate was observed under microwave conditions. Furthermore, recycling of the ionic liquid catalyst could be performed after simply distilling off the products. 相似文献